The for command in the command interpreter (COMMAND.COM) is modal. The default is LFNFOR=OFF, which causes the for command to use the old Interrupt 21h function calls. In that case, only aliases (8.3 filenames) can be used in the for command. If LFNFOR=ON is set, the for command uses the new Interrupt 21h functions, and long filenames can be used as part of the for command.